CKA Storage Practice Question
Which TWO of the following are valid access modes for a PersistentVolume in Kubernetes? (Select two.)
⚠ Common exam trap
Candidates often confuse the valid access modes with similar-sounding but non-existent modes like 'WriteMany' or 'ReadWriteOncePerNode', which are not part of the Kubernetes API specification.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
ReadWriteOnce
ReadWriteOnce (C) is a valid PersistentVolume access mode, meaning the volume can be mounted as read-write by a single node at a time. ReadWriteMany (D) is also valid, allowing the volume to be mounted as read-write by many nodes simultaneously. These are two of the four standard Kubernetes access modes, alongside ReadOnlyMany and ReadWriteOncePod. WriteMany (A) is not a valid mode because the read/write distinction is missing. ReadOnlySingle (B) is invalid since the correct read-only mode is ReadOnlyMany. ReadWriteOncePerNode (E) is not a real access mode; the per-node semantics are already covered by ReadWriteOnce.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
WriteMany
Why it's wrong here
WriteMany is not a valid PersistentVolumeAccessMode constant in Kubernetes. The API server only accepts the predefined modes ReadWriteOnce (RWO), ReadOnlyMany (ROX), ReadWriteMany (RWX), and the newer ReadWriteOncePod. If you use WriteMany in a PersistentVolume or PersistentVolumeClaim manifest, the request will be rejected as invalid. The behavior you might intend—allowing multiple nodes to write—is already covered by ReadWriteMany, which also includes read access.
- ✗
ReadOnlySingle
Why it's wrong here
ReadOnlySingle does not correspond to any mode in the Kubernetes access-mode enum. Standard access modes combine read/write intent with node scope: RWO, ROX, RWX, and ReadWriteOncePod. A single-node read-only mount is not separately represented as a constant; if you need that behavior, you would use RWO and then set readOnly: true in the Pod's volumeMount definition. Using this non-standard string would cause validation errors and prevent PVC binding.
- ✓
ReadWriteOnce
Why this is correct
ReadWriteOnce (RWO) is a valid access mode that allows a volume to be mounted with read-write access on a single node. Multiple Pods running on that same node can concurrently use the volume, but while it is attached to that node, no other node can mount it. This mode is typical for block storage like AWS EBS or Google Persistent Disks, which are designed for single-node attachment and do not support multi-node reads or writes.
- ✓
ReadWriteMany
Why this is correct
ReadWriteMany (RWX) is a valid access mode that permits the volume to be mounted with read-write access on many nodes simultaneously. It is required for shared filesystems such as NFS, CephFS, or GlusterFS, where Pods across different nodes need concurrent read and write operations on the same data. Unlike RWO, RWX does not restrict the volume to a single node, and unlike ROX, it allows write operations from every mounted client.
- ✗
ReadWriteOncePerNode
Why it's wrong here
ReadWriteOncePerNode is not a standard PersistentVolumeAccessMode; it is not defined in Kubernetes and will be rejected by the API server. The closest valid mode is ReadWriteOncePod, introduced in v1.22, which restricts a volume to a single Pod, not to one node. The phrase 'per node' is misleading: if only one node may mount the volume read-write, then RWO is the correct mode; if multiple nodes are allowed, you need RWX. There is no access mode that is 'RWO per each node'.
Go deeper
Related to this question
Learn chapter
Troubleshooting Cluster and Node Issues
Key term
Volumes
In Kubernetes, a volume is a storage resource that outlives the pod it belongs to, enabling data to persist across container restarts and be shared between containers in the same pod.
Key term
Network Policies
A Kubernetes resource that controls how pods communicate with each other and with other network endpoints, acting as a firewall for pod-to-pod traffic.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CKA practice question is part of Courseiva's free CNCF certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CKA exam.